Two pre-existing functional Core Facilities will be merged under this proposal and focused on supporting the UPENN/CHOP program in benign hematopoiesis. This combined service will be entitled the Human Stem Cell Core B and will be directed by Dr. Mitchell Weiss. The two SubCores are 1) SubCore B-1, the Hematopoietic Stem Cell (HSC) Facility at UPENN, directed by Martin Carroll, and 2) SubCore B-2, the Human Embryonic Stem (ES) and Induced Pluripotent Stem (iPS) Cell Facility, which is physically present at CHOP, and will be directed by Dr. Deborah French.